Exercise as it relates to Disease/High intensity interval training for fat loss

An analysis of the journal article 'The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women' by Trapp et al (2008) **For the purpose of this analysis fat loss will be predominately spoken about**



What is the background to this research?
Obesity is now a worldwide crisis, it is an issue spread to both developed and developing countries. It has been approximated that 250million roughly 7% of the world's population are obese and that is set to increase in the future Obesity is defined as and recognised internationally in an adult population as having a Body Mass Index (weight/height2) of ≥ 30.

We know obesity is associated to long-term health difficulties and reduced quality of life thus it is important to apply effective strategies to reduce weight-loss. Although diet and caloric restriction are appropriate weigh-loss strategies exercise programs can similarly play a crucial role in weight reduction. Commonly, exercise programs designed for weight/fat loss are solely focused on steady-state exercise (SSE) which involves training being performed at a low intensity for longer duration, typically lasting approximately 30minutes. This is indicated by the image above which references the weight control or fat burning zone. Commonly this style of exercise program has been shown to have little to to no effects on fat loss, therefore the need to develop a training program which is more effective for fat loss is needed.

Can high intensity interval training(HIIT) be more beneficial for fat loss than SSE? HIIT involves short bouts of high-intensity anaerobic exercise followed by longer bouts of low-intensity aerobic exercise. Previous research has proposed to examine this theory Trembly et.al which looked at comparing HIIT to endurance training over the course of 20 weeks, this study found that upon completion of the training regime the HIIT group had lost significantly more fat when measuring skin folds, however the HIIT group were training over a long duration (45min). Research by Trapp et.al proposed to examine the effects of 20-min bouts of HIIT repeated three times a week on body composition, in hope to develop a program that already physically inactive, overweight individuals could adhere to and be a less demanding version that would reduce fat mass.

Where is the research from?
Research was conducted through the Faculty of Medicine at the University of New South Wales and the Garvan Institute, Sydney, New South Wales conducted the research. The research was published in the International Journal of Obesity (2008)

What kinds of research was this?
The research was a qualitative, small-scaled randomized controlled trial.

What did the research involve?
Research was aimed at assessing the effects a 15-week long high-intensity interval training regime had on fat loss and insulin resistance in young women.

The forty-five participants were non-smoking, inactive but otherwise healthy women, the women had a mean BMI of 23.2 ± 2.0 and the age of 20.2 ± 2.0 years. Subjects were screened using a standard pre-exercise questionnaire. Then participants were randomly assigned one of three groups: High-intensity interval training, steady-state exercise or control group. Only the HIIT & SSE groups participated in the 15-week program, The control group was asked to maintain their current levels of physical activity and dietary habits for 15 weeks.

Subjects were exposed to pre-training testing that involved anthropometric measures as well as a determination of VO2 peak on a cycle ergometer. Exercise was carried out on an electrically braked, computer controlled Monark 839 cycle ergometer.

The HIIT involved subjects performing 8 seconds of sprinting followed by 12 seconds of turning the pedals over slowly for a maximum of 60 repeats a session. Resistance was increased as the subjects adapted to the workload.

SSE training involved exercising at 60% of their established VO2 peak, subjects started the 15-week program exercising at this intensity for 15-20minutes and over the course of the 15 weeks gradual increase saw a exercise session lasting 40minutes.

What were the basic results?
Both the HIIT & SSE groups significantly improved their cardiovascular fitness upon completion of the training regime, however the HIIT group only showed significant loss in total and abdominal fat. The fat loss within the HIIT group was variable, leaner women lost less fat than the overweight women. The fat loss induced by high-intensity interval training was however achieved with half the time commitment but with similar energy expenditure.

How did the researchers interpret the results?
The research was interpreted with results based on individual changes to fat stored around the body after exposure to one of the three groups for the duration of the 15-week program. Measurements were taken of total body mass, fat mass, trunk fat as well as both leg and arm fat and changes to these figures were used to justify the research.

What conclusions should be taken away from this research?
This research indeed demonstrates that High Intensity Interval Training is very beneficial for fat loss. Despite half the time commitment the HIIT group lost 11.2% total fat mass while the SSE experienced no fat loss. It can be concluded that HIIT performed three times per week for 15 weeks compared to the same frequency of SSE exercise did equate to reductions in totally body fat, as well as trunk and leg fat and this training method is both effective and efficient in reducing body composition.

What are the implications of this research?
Exercise programs on top of diet and caloric restriction are essential to maintaining or controlling body composition, with the world wide obesity numbers as high as they are this issue needs to be addressed. It is commonly accepted that long duration steady state exercise performed at light to moderate intensities are the most beneficial for burning and controlling fat. This study provides us with enough evidence to support the case that high intensity interval training is indeed a more effective training program than a steady state exercise regime. HIIT as a training protocol can be carried out by the general public with little to no extra effort, this research showed that from a time perspective more can be achieved in less time when participating in this style of exercise. Considerations can be made in respect to the small scale population and that only women were tested, if future testing into HIIT were to take place a larger population and testing of males is required.